The present invention relates to a plastic case formed by mating upper and lower half cases together and then welding (fusingly bonding) the two half cases together. More particularly, the invention relates to a type of plastic case which is relatively small and accordingly has limited welding spaces available.
In recent years, there have been manufactured a wide variety of products formed from plastic resins. One type of such product is a box-like case containing desired components therein. For example, a plastic case containing a recording medium such as a disk or a tape is used to form a box-like body as in a magnetic disk cartridge, a magneto-optical disk cartridge, and a magnetic tape cassette such as a video tape cassette or an audio tape cassette. This plastic case, although relatively small, is required to have high molding accuracy. The case is formed by mating upper and lower half o cases together.
With respect to magnetic tape cassettes, the manner of for example, in Japanese Laid-Open (Kokai) Patent Applications Nos. 37913/72 and 98604/79 and Japanese Laid-Open Utility Model Applications Nos. 102085/82 and 871/89. if an associated part contained in this case is, for example, a magnetic disk or a magnetic tape, the fine particles will adhere onto the recording surface of such media, resulting in a degradation of the recording and reproducing characteristics, and causing undesired phenomena such as drop-out in its output level.